Human growth hormone (hGH), also known as somatropin (INN) or somatotropin, is a protein hormone produced and secreted by the somatotropic cells of the anterior pituitary. Human growth hormone plays a key role in somatic growth in childhood and in metabolism in adulthood through its effects on the metabolism of proteins, carbohydrates and lipids. Human growth hormone is a single polypeptide chain of 191 amino acids having two disulfide bonds, one between Cys-53 and Cys-165, forming a large loop in the molecule, and the other between Cys-182 and Cys-189, forming a small loop near the C-terminus.
Recombinant DNA technology has permitted the production of an unlimited supply of hGH in a number of different systems. One such system is bacteria, for example E. coli. Although such a process is well established and widely used, as any process of technology at all times, also the latter can still be improved upon.
When recombinant hGH is expressed in E. coli cells as inclusion bodies, the inclusion bodies are typically dissolved in the presence of reducing agents and/or chaotropic agents thereby fully renaturing the hGH and facilitating proper folding of the hGH into its bioactive form and mitigating aggregate formation.